Methods of forming graphene-containing switches

ABSTRACT

Some embodiments include methods of forming graphene-containing switches. A bottom electrode may be formed over a base, and a first electrically conductive structure may be formed to extend upwardly from the bottom electrode. Dielectric material may be formed along a sidewall of the first electrically conductive structure, while leaving a portion of the bottom electrode exposed. A graphene structure may be formed to be electrically coupled with the exposed portion of the bottom electrode. A second electrically conductive structure may be formed on an opposing side of the graphene structure from the first electrically conductive structure. A top electrode may be formed over the graphene structure and electrically coupled with the second electrically conductive structure. The first and second electrically conductive structures may be configured to provide an electric field across the graphene structure.

RELATED PATENT DATA

This patent resulted from a continuation of U.S. patent application Ser.No. 13/191,192, which was filed Jul. 26, 2011, which issued as U.S. Pat.No. 8,394,682, and which is hereby incorporated herein by reference.

TECHNICAL FIELD

Methods of forming graphene-containing switches.

BACKGROUND

A switch is a component utilized to reversibly open and close a circuit.A switch may be considered to have two operational states, with one ofthe states being an “on” state and the other being an “off” state.Current flow through the switch will be higher in the “on” state that inthe “off” state, and some switches may permit essentially no currentflow in the “off” state. Switches may be utilized anywhere in anintegrated circuit where it is desired to reversibly open and close aportion of the circuit.

It would be desirable to develop improved methods for fabricatingswitches suitable for utilization in integrated circuitry, and it wouldbe further desirable to develop improved methods for forming switchessuitable for utilization as select devices in memory devices (such asmemory arrays).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic, cross-sectional side view of an exampleembodiment switch.

FIG. 2 is a diagrammatic, three-dimensional view of an exampleembodiment graphene structure that may be utilized in the switch of FIG.1.

FIG. 3 is a diagrammatic, cross-sectional side view of another exampleembodiment switch.

FIG. 4 is a diagrammatic, cross-sectional view of a constructioncomprising a pair of example embodiment switches.

FIGS. 5-11 are diagrammatic, cross-sectional views of a portion of aconstruction at various stages of an example embodiment method forfabricating a graphene-containing switch.

FIGS. 12-15 are diagrammatic, cross-sectional views of a portion of aconstruction at various stages of an example embodiment method forfabricating a plurality of graphene-containing switches within a singleopening.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Some embodiments pertain to methods of forming graphene-containingswitches.

A portion of an integrated circuit construction 10 is illustrated inFIG. 1, showing an example embodiment graphene-containing switch 12supported by a base 14. Although the base is shown to be homogeneous,such base may comprise numerous components and materials in variousembodiments. For instance, the base may comprise a semiconductorsubstrate supporting various materials and components associated withintegrated circuit fabrication. Example materials that may be associatedwith the substrate include one or more of refractory metal materials,barrier materials, diffusion materials, insulator materials, etc. Thesemiconductor substrate may, for example, comprise, consist essentiallyof or consist of monocrystalline silicon. The terms “semiconductivesubstrate,” “semiconductor construction” and “semiconductor substrate”mean any construction comprising semiconductive material, including, butnot limited to, bulk semiconductive materials such as a semiconductivewafer (either alone or in assemblies comprising other materials), andsemiconductive material layers (either alone or in assemblies comprisingother materials). The term “substrate” refers to any supportingstructure, including, but not limited to, the semiconductive substratesdescribed above.

The switch 12 includes a first electrode 16 and a second electrode 18.Such electrodes are spaced apart from one another, and specifically areseparated from one another by a space 22 in the shown embodiment.

The electrodes 16 and 18 comprise electrically conductive electrodematerial 20. Such electrode material may comprise any suitableelectrically conductive composition, or combination of compositions; andmay, for example, comprise one or more of various metals (for instance,tungsten, titanium, copper, etc.), metal-containing materials (forinstance, metal silicide, metal carbide, metal nitride, etc.), andconductively-doped semiconductor materials (for instance,conductively-doped silicon, conductively-doped germanium, etc.).Although both of the electrodes 16 and 18 are shown comprising the sameelectrically conductive material, in other embodiments the electrodes 16and 18 may comprise different conductive materials relative to oneanother.

A graphene structure 24 extends between the electrodes. The graphenestructure may be referred to as extending longitudinally between theelectrodes; with the term “longitudinally” being used to designate anorientation of the graphene structure to which other components may becompared. For instance, the electrodes 16 and 18 may be considered to bespaced from one another along the longitudinal dimension of the graphenestructure; and the graphene structure may be considered to have athickness, “T”, along a lateral dimension which extends orthogonally tothe longitudinal dimension. The “longitudinal” dimension of the graphenestructure may be any part of the graphene structure designated as such;and may or may not be the longest dimension of the graphene structure.

In the shown embodiment, the graphene structure extends across the space22, and directly contacts both of the electrodes 16 and 18. In someembodiments, the graphene structure will comprise more than one layer ofgraphene. For instance, the graphene structure may be a multi-layer(e.g., bilayer) structure. A dashed-line 25 is shown within thestructure 24 to diagrammatically illustrate that such structure maycomprise more than one layer of graphene in some embodiments. The layersmay be the same thickness, or may be different thicknesses relative toone another.

In operation, current flows along the graphene structure 24 between theelectrodes 16 and 18 when the switch 12 is in an “on” state. Suchcurrent flow may be considered to be along the direction of an axis 27.

The switch 12 comprises a pair of nodes 26 and 28, with such nodes beinglaterally outward of the graphene structure and on opposing sides of thegraphene structure 24 in the shown embodiment. The nodes compriseelectrically conductive material 30. Such electrically conductivematerial may comprise any suitable composition, including any of thecompositions described above with reference to the electrodes 16 and 18.Although the nodes 26 and 28 are shown comprising a same composition asone another, in some embodiments the nodes may comprise differentcompositions relative to one another.

The nodes 26 and 28 are connected to circuitry 32 and 34, respectively,with such circuitry being configured to generate an electric field (EF)between the nodes. Such electric field is transverse to a direction ofcurrent flow along graphene structure 24. Although the electric field isillustrated as being oriented from electrode 28 toward electrode 26, theelectric field may be oriented in an opposite direction in otherembodiments. The field EF may be comprised by an electric field that isprimarily orthogonal to the graphene structure (as shown), or may becomprised by an electric field that is primarily at an angle other thanorthogonal to the graphene structure. If an electric field is primarilyat an angle other than parallel to the direction of current flow alongthe graphene structure (i.e., a direction other than along axis 27),such electric field will have a vector component that corresponds to theillustrated field EF which is transverse to the direction of currentflow along graphene structure 24. Thus, the generation of an electricfield that is directed primarily along any direction other than parallelto the axis 27 may be considered to comprise generation of an electricfield transverse to the direction of current flow along graphenestructure 24. It is noted that an electric field component along axis 27(i.e., parallel to a direction of current flow along graphene structure24) may be useful to assist in moving electrons from electrode 16 to 18,or vice versa, in the “on” state of the switch.

The nodes 26 and 28 may be considered together as an electricalcomponent configured to alter a bandgap within graphene of the graphenestructure 24. Specifically, the electric field generated between thenodes may alter the bandgap within graphene of the graphene structure 24by taking advantage of a relationship described by Feng Wang (see, forexample, Zhang, et. al., Nature 459, 820-823 (11 Jun. 2009)), whereupona bandgap within the graphene is increased by increasing the electricfield between the nodes 26 and 28.

Manipulation of the magnitude of the electric field transverse tocurrent flow within the graphene structure 24 may be used to control thestate of the switch. A relatively high transverse electric field may beutilized to maintain the switch 12 in an “off” state, while a relativelylow transverse electric field may be utilized to maintain the switch 12in an “on” state. The terms “relatively high transverse electric field”and “relatively low transverse electric field” are utilized to indicatethat the transverse electric fields are low and high relative to oneanother. In some embodiments, the total voltage differential between thenodes 26 and 28 may be changed by about 0.25 eV to transition the switchfrom the “on” state to the “off” state, or vice versa. In someembodiments, the transition from the “on” state to the “off” state maybe achieved by providing a transverse electric field of less or equal toabout 3 volts/nanometer, and in some embodiments may be achieved byproviding a transverse electric field of less or equal to about 2volts/nanometer.

The graphene structure 24 has a length “L” from electrode 16 toelectrode 18, and the thickness “T” along a direction orthogonal to thelength. The length and thickness of the graphene structure may betailored to achieve desired performance characteristics; andadditionally the spacing between nodes 26 and 28, and the direction ofthe electric field generated between such nodes, may be tailored toachieve desired performance characteristics.

In some embodiments, the graphene structure 24 will have a maximumoverall thickness between the nodes 26 and 28 of less than about 5nanometers. In some embodiments, the graphene structure will comprisetwo or more layers, and at least one of the layers will have a maximumthickness between the nodes of less than about 5 nanometers; and in someembodiments all of such layers will have a maximum thickness between thenodes of less about 5 nanometers. In some embodiments, the individuallayers of graphene will have thicknesses within a range of from at leastabout 1 nanometer to at least about 5 nanometers.

In some embodiments, the graphene structure 24 will have a length “L”within a range of from at least about 10 nanometers to at least about 50nanometers.

In some embodiments, the graphene structure 24 may berectangular-shaped. An example rectangular-shaped graphene structure isshown in FIG. 2. Such structure has the length “L” and the thickness “T”discussed above, and in addition has a width “W”. The width may betailored, in addition to the thickness and length, to achieve desiredbandgap characteristics in the graphene, and desired performancecharacteristics of the switch 12 (FIG. 1). In some embodiments, thegraphene structure 24 will have a width “W” of from at least about 5nanometers to at least about 20 nanometers.

In some embodiments, the graphene structure may be thin enough to havean inherent bandgap; and may, for example, be a strip having a narrowdimension (for instance, a dimension of less than or equal to about 20nanometers, less than about 10 nanometers, or even less than or equal toabout 5 nanometers). A relationship between graphene strip dimensionsand bandgap is described in several articles by H. Dai (for instance, Liet. al., Science 319, 1229-1232 (2008)).

The graphene structure 24 may be configured relative to the electricfield “EF” of the switch 12 of FIG. 1 so that the electric field extendsprimarily along the thickness “T” of the graphene structure (as shown inFIG. 1), or may be rotated relative to the configuration of FIG. 1 sothat the electric field extends primarily along the width “W” of thegraphene structure, or may be rotated so that the electric field extendsthrough the graphene structure along a primary direction which is angledrelative to both the thickness and the width of the graphene structure.

In some embodiments, the graphene structure 24 may comprise two or moregraphene layers which are dimensionally configured to take advantage ofthe relationship described by H. Dai so that the graphene has aninherent bandgap in the absence of a transverse electric field. Such canprovide an additional parameter to tailor the conductivity of the “on”state mode of switch 12 for particular applications. In otherembodiments, the graphene structure 24 may comprise one or more layerswhich all individually have dimensions too large for a significantbandgap to be within the graphene of the structure 24 in the absence ofan applied transverse electric field. Such can enable the graphenestructure to have very high conductance in the “on” state mode of theswitch.

A dielectric material 40 is shown within the space between theelectrodes 16 and 18, and surrounding the nodes 26 and 28. Thedielectric material may comprise any suitable composition or combinationof compositions, and in some embodiments may comprise one or more ofsilicon dioxide, silicon nitride, and any of various doped silicateglasses (for instance, borophosphosilicate glass, phosphosilicate glass,fluorosilicate glass, etc.). Although the dielectric material 40 isshown to be homogeneous throughout the switch 12, in other embodimentsmultiple different dielectric materials may be utilized.

The nodes 26 and 28 may be connected to any suitable circuitry to enablethe transverse electric field to be generated across the graphenestructure 24. In some embodiments, each of the nodes may be conductivelycoupled to one of the electrodes 16 and 18. An example of suchembodiments is described with reference to a construction 10 a shown inFIG. 3. Such construction comprises a switch 12 a analogous to theswitch 12 described above with reference to FIG. 1.

The switch 12 a comprises an upwardly-extending electrically conductivestructure 42 electrically coupled with the bottom electrode 16, andcomprises a downwardly-extending structure 44 electrically coupled withthe top electrode 18. The nodes 26 and 28 are effectively comprised byportions of the structures 42 and 44 that vertically overlap one anotherin the illustrated configuration.

The structures 42 and 44 may comprise any suitable electricallyconductive materials, and may comprise the same material as one anotheror different materials relative to one another. Also, the structures 42and 44 may comprise common materials as the electrodes 16 and 18, or oneor both of the structures 42 and 44 may comprise different materialsrelative to one or both of the electrodes 16 and 18.

In some embodiments, it may be advantageous to tightly pack a pluralityof switches over a semiconductor substrate. FIG. 6 shows a construction45 having a pair of switches 12 a (of the type described above withreference to FIG. 2) packed next to one another. In the shownembodiment, the switches are mirror images of one another along avertical plane 31. In some embodiments, such configuration may enabletwo adjacent switches to be formed in a common trench.

Some embodiments include methods of forming switches of the varioustypes described above with reference to FIGS. 1-4. FIGS. 5-11 illustrateprocess stages of a first embodiment method which may be utilized tofabricate switch-containing constructions analogous to the constructiondescribed above with reference to FIG. 3, and FIGS. 12-15 illustrateprocess stages of a second embodiment method which may be utilized tofabricate constructions analogous to the multi-switch constructiondescribed above with reference to FIG. 4.

Referring to FIG. 5, a construction 50 is shown to comprise a base 14and a bottom electrode 16 supported over such base. The base 14 maycomprise any of the configurations discussed above with reference toFIGS. 1-4. The electrode 16 may comprise any suitable material, and isshown to comprise a material 20 of the type described above withreference to FIG. 1. In the shown embodiment, the bottom electrode islaterally surrounded by a dielectric material 52. The dielectricmaterial 52 may comprise any suitable electrically insulativecomposition or combination of compositions; and in some embodiments maycomprise, consist essentially of, or consist of one or more of silicondioxide, silicon nitride and any of various doped silicate glasses.

A dielectric material 54 is formed across the bottom electrode 16 andthe dielectric material 52, and an opening 56 is patterned withinmaterial 54 to expose an upper surface 17 of the bottom electrode. Theopening 56 may be formed utilizing any suitable processing. Forinstance, in some embodiments material 54 may be initially formed tocover an entirety of the upper surface of electrode 16, and subsequentlyopening 56 may be formed by etching through material 54 while utilizinga photolithographically-patterned photoresist mask (not shown) to definea location of the opening. The mask may then be removed with subsequentprocessing.

The opening 56 has a pair of sidewalls 55 and 57 when viewed along thecross-section of FIG. 5. Such sidewalls may merge in a location outsideof the plane of the FIG. 5 view so that the apparent pair of sidewallsis actually a single sidewall that extends around opening 56.

Referring to FIG. 6, a dielectric spacer 58 is formed along a bottomregion of the sidewall 55. The dielectric spacer may be formed utilizingany suitable processing. For instance, a layer of dielectric materialmay be formed conformally over material 54 and within opening 56, andsuch layer may be patterned utilizing one or morephotolithographically-patterned masks (not shown) and suitable etchingto create the spacer 58. The spacer 58 may comprise any suitabledielectric composition or combination of compositions; and in someembodiments may comprise, consist essentially of, or consist of one ormore of silicon dioxide, silicon nitride, and any of various dopedsilicate glasses.

Referring to FIG. 7, electrically conductive liners 60 and 62 are formedalong the sidewalls 55 and 57. The liners 60 and 62 may comprise anysuitable electrically conductive composition or combination ofcompositions; and in some embodiments may comprise, consist essentiallyof, or consist of one or more of various metals, metal-containingcompositions, and conductively-doped semiconductor materials.

The liners 60 and 62 may be formed with any suitable processing. Forinstance, a layer of electrically conductive material may be formed overdielectric 54 and within opening 56, and then subjected to ananisotropic etch to form the illustrated liners. In some embodiments,chemical-mechanical polishing (CMP) may be utilized after theanisotropic etch to form the illustrated planarized upper surfaceextending across the material 54 and the liners 60 and 62.

Referring to FIG. 8, a top portion of liner 60 is replaced with adielectric spacer 64. Such replacement may be accomplished utilizing anysuitable processing. For instance, a patterned mask (not shown) may beformed to protect liner 62 while exposing liner 60 to an anisotropicetch which removes the top portion of liner 62. Subsequently, dielectricmaterial may be formed over the remainder of liner 60 and patterned toform the shown dielectric spacer 64. In some embodiments, dielectricspacers 58 and 64 may be referred to as first and second dielectricspacers, respectively.

The liners 60 and 62 may be referred to as first and second electricallyconductive structures, respectively; and such structures are directlyover the bottom electrode. In the shown embodiment, the firstelectrically conductive structure 60 directly contacts the bottomelectrode 16, and the second electrically conductive structure 62 doesnot directly contact the bottom electrode. Instead, the secondelectrically conductive structure is spaced from the bottom electrode bydielectric spacer 58.

A dielectric liner 66 is formed along a sidewall of electricallyconductive structure 62. The dielectric liner may be formed utilizingany suitable processing. For instance, the dielectric liner may beformed by providing dielectric material across an entirety ofconstruction 50, and then subsequently patterning such materialutilizing a patterned mask (not shown) and one or more suitable etches.Subsequently, CMP may be utilized to form the illustrated planarizedupper surface extending across material 54, liner 62, spacer 64 andliner 66.

The liner 66 may comprise any suitable electrically insulativecomposition or combination of compositions; and in some embodiments maycomprise, consist essentially of, or consist of one or more of silicondioxide, silicon nitride and any of various doped silicate glasses.

Although the liner 66 is shown formed against conductive structure 62,in other embodiments the liner may be formed against the otherconductive structure 60.

After liner 66 is formed, the opening 56 is narrowed by the variousstructures 58, 60, 62, 64 and 66. The bottom electrode 16 has a portion68 exposed within the narrowed opening, and has another portion coveredby the various structures 58, 60, 62, 64 and 66.

Referring to FIG. 9, a graphene structure 70 is formed along a sidewallof dielectric liner 66. The graphene structure directly contacts theexposed portion 68 of bottom electrode 16, and thus is directlyelectrically coupled with the bottom electrode in the shown embodiment.The graphene structure 70 is analogous to the structure 24 discussedabove with reference to FIG. 3, and may comprise any suitablecomposition. For instance, the graphene structure may comprise a singlegraphene layer in some embodiments; and may comprise multiple graphenelayers in other embodiments (e.g., may be a bilayer structure in someembodiments).

The graphene structure 70 may be formed utilizing any suitableprocessing. For instance, a suitable seed material may be formed alongdielectric spacer 66, and then graphene may be epitaxially grown fromsuch a seed material. Example seed materials may include silicon carbideand/or various metals (for instance, ruthenium, iridium, etc.).Alternatively, a graphene precursor may be formed along dielectricspacer 66 and then converted to graphene. An example graphene precursoris graphite oxide, which may be converted to graphene utilizing one ormore suitable reductants (for instance, hydrazine).

In the shown embodiment, the graphene structure 70 is formed only alonga sidewall of dielectric liner 66. In some embodiments, such may beaccomplished by providing appropriate seed material and/or precursoronly along the sidewall of the dielectric liner. For instance, the seedmaterial and/or precursor may be deposited over the top of the liner 66as well as along the sidewall, and then subjected to anisotropic etchingto leave the seed material and/or precursor only along the sidewall.Alternatively, in some embodiments the graphene structure may beinitially formed to extend across an upper surface of the dielectricliner, and possibly even across an upper surface of the electricallyconductive structure 62. The graphene structure may then be removed fromover the upper surfaces utilizing CMP, anisotropic etching, and/or otherappropriate processing to form the construction shown in FIG. 9.

Although the electrically conductive structures 60 and 62 are describedas being simultaneously formed at the processing stage of FIG. 7, inother embodiments the conductive structures may be sequentially formed.For instance, structure 62 may be formed at the processing stage of FIG.7 and structure 60 may be formed at a processing stage subsequent toformation of one or both of the dielectric liner 66 and the graphenestructure 70.

After formation of graphene structure 70, a portion of opening 56remains along the electrically conductive structure 60 and dielectricspacer 64 (specifically, such opening is on an opposing side of graphenestructure 70 from the dielectric liner 66). The opening is subsequentlyfilled with dielectric material 72, as shown in FIG. 10.

A planarized upper surface 73 extends across construction 50 at theprocessing stage of FIG. 10. Such planarized upper surface may be formedwith any suitable processing, such as, for example, CMP. Planarizedupper surfaces of construction 50 are illustrated at all of the variousprocess stages of FIGS. 6-10 in the illustrated example embodiment. Inother embodiments, various of the materials provided at the processstages of FIGS. 6-10 may be left with non-planarized upper surfaces, andthen planarization may be conducted after formation of the finalmaterial utilized to fill opening 56 (material 72 in the shown exampleembodiment) to form the planarized upper surface 73 of FIG. 10.

Referring to FIG. 11, the top electrode 18 is formed on the planarizedupper surface 73. The top electrode 18 is shown comprising electricallyconductive material 20. The top electrode may be formed utilizing anysuitable processing. For instance, material 20 may be formed across anentirety of upper surface 73 and then patterned utilizing aphotolithographically-patterned photoresist mask (not shown) and one ormore suitable etches to form the patterned top electrode 18 of FIG. 11.

The top electrode 18 is electrically coupled with thedownwardly-extending electrically conductive structure 62, and thebottom electrode 16 is electrically coupled with the upwardly-extendingelectrically conductive structure 60. Accordingly, the construction ofFIG. 11 comprises a switch 12 a analogous to the switch of FIG. 3, withthe structures 60 and 62 being analogous to the structures 42 and 44 ofFIG. 3. In operation, the structures 60 and 62 provide an electric fieldacross the graphene structure 70 so that the switch of FIG. 11 may beoperated analogously to the switch described above with reference toFIG. 3.

The integrated switch 12 a may be utilized in any suitable application.In an example application, the switch may be representative of aplurality of substantially identical switches that are simultaneouslyfabricated across a semiconductor construction for utilization as selectdevices in a memory array.

FIGS. 12-15 illustrate another example process for fabricatinggraphene-containing switches.

Referring to FIG. 12, a construction 100 comprises a base 14 and a pairof spaced apart bottom electrodes 16 supported over such base. The base14 and electrodes 16 may comprise any of the configurations andcompositions discussed above with reference to FIGS. 1-4.

The bottom electrodes are shown to be patterned within a dielectricmaterial 102. The dielectric material 102 may comprise any suitableelectrically insulative composition or combination of compositions; andin some embodiments may comprise, consist essentially of, or consist ofone or more of silicon dioxide, silicon nitride and any of various dopedsilicate glasses.

A dielectric material 104 is formed across the bottom electrodes 16 andthe dielectric material 102, and an opening 106 is patterned withinmaterial 104 to expose upper surfaces of the bottom electrodes. Theopening 106 may be formed utilizing any suitable processing; including,for example, processing analogous to that described above with referenceto FIG. 5 for forming the opening within material 56.

Upwardly-extending electrically conductive structures 108 and 110 areformed along sidewalls of opening 106, and directly against uppersurfaces of the electrodes 16. The electrically conductive structures108 and 110 may be formed with processing analogous to that describedabove with reference to FIG. 7 for fabrication of the structures 60 and62.

The electrically conductive material of the structures 108 and 110 hasbeen recessed relative to the top of material 104. Accordingly,uppermost surfaces 109 and 111 of the upwardly-extending structures 108and 110 are below the top of opening 106 (i.e., are below the topsurface of dielectric material 104).

A dielectric material 112 is patterned into liners 114 that extend alongsidewalls of conductive structures 108 and 110, and over the topsurfaces of the conductive structures. The liners 114 may be formedutilizing any suitable processing. For instance, material 112 may beformed over material 104, along the sidewalls of structures 108 and 110,and across a bottom surface of opening 106; and may then be subjected toanisotropic etching either alone, or in combination with the utilizationof a patterned mask (not shown) to pattern material 112 into the liners114.

In the shown embodiment, the dielectric material 112 may be consideredto form spacers over the structures 108 and 110 analogous to the spacer64 of FIG. 8, and to also form liners along sidewalls of the conductivestructures analogous to the liner 66 of FIG. 9.

In some embodiments, the dielectric materials 104 and 114 may bereferred to as first and second dielectric materials, respectively.

Referring to FIG. 13, graphene-containing structures 116 are formedalong sidewalls of the liners 114. The graphene-containing structuresmay be formed with any suitable processing, including, for example,processing analogous to that described above with reference to FIG. 9for fabrication of structure 70. Thus, the graphene-containingstructures may be formed by, for example, epitaxial growth of graphenefrom suitable seed material and/or conversion of a suitable precursorinto graphene. The graphene-containing structures may extend only alongthe sidewalls of liners 114 (as shown), or may extend across uppersurfaces of one or both of materials 104 and 112 in other embodiments.

The graphene-containing structures 116 directly contact the bottomelectrodes 16, and thus are electrically coupled with such bottomelectrodes.

Referring to FIG. 14, dielectric material 118 is formed to extend overdielectric materials 104 and 112, along the sidewalls ofgraphene-containing structures 116, and across a bottom of opening 106.The dielectric material 118 may comprise any suitable composition orcombination of compositions, and may, for example, comprise any of thecompositions discussed above relative to the material 72 of FIG. 10. Insome embodiments, the dielectric material 118 may be referred to as athird dielectric material to distinguish it from the first and seconddielectric materials 104 and 112.

In the shown embodiment, regions of the bottom electrode 16 remainedexposed after formation of graphene-containing structures 116 at theprocessing stage of FIG. 13, and the dielectric material 118 of FIG. 14covers such exposed regions.

A conductive material 120 is patterned into electrically conductivestructures 122 along lateral surfaces of dielectric material 118. Thematerial 120 may be patterned into the shown electrically conductivestructures with any suitable processing. For instance, material 120 maybe formed conformally across dielectric material 118, and may then besubjected to anisotropic etching to pattern material 120 into theillustrated conductive structures 122. Ultimately, structures 122 willbecome downwardly-extending conductive structures analogous to thestructures 44 of FIG. 4. The structures 122 are spaced from the bottomelectrodes 16 by the dielectric material 118 in the shown embodiment. Inother embodiments the structures 122 may be spaced from the bottomelectrodes with dielectric spacers fabricated analogously to the spacer58 of FIGS. 6-11.

A dielectric material 124 is formed across materials 118 and 120, andwithin a gap between the structures 122 to fill the opening 106. Thedielectric material 124 may comprise any suitable composition orcombination of compositions; and in some embodiments may comprise,consist essentially of, or consist of one or more of silicon dioxide,silicon nitride and any of various doped silicates. In some embodiments,the dielectric material 124 may be referred to as a fourth dielectricmaterial.

Referring to FIG. 15, construction 100 is subjected to planarization(for instance, CMP) to form a planarized upper surface 125 extendingacross the graphene structures 116 and the conductive structures 122. Apair of top electrodes 18 are formed on planarized upper surface 125.The top electrodes are directly against the graphene-containingstructures 116 and the electrically conductive structures 122; and thusare electrically coupled with the graphene-containing structures 116 andthe electrically conductive structures 122. The top electrodes arespaced from the conductive structures 108 and 110 by the dielectricmaterial 112, and thus are not electrically coupled with theelectrically conductive structures 108 and 110.

The construction of FIG. 15 is analogous to that of FIG. 4, and thuscomprises a pair of switches 12 a packed next to one another. In theshown embodiment, the switches are mirror images of one another alongthe vertical plane 31. The processing of FIGS. 12-15 forms a pluralityof switches 12 a within a single opening 106. Although the shownprocessing forms a pair of switches, analogous processing may beutilized to form more than two switches within a single opening.

The particular orientation of the various embodiments in the drawings isfor illustrative purposes only, and the embodiments may be rotatedrelative to the shown orientations in some applications. The descriptionprovided herein, and the claims that follow, pertain to any structuresthat have the described relationships between various features,regardless of whether the structures are in the particular orientationof the drawings, or are rotated relative to such orientation.

The cross-sectional views of the accompanying illustrations only showfeatures within the planes of the cross-sections, and do not showmaterials behind the planes of the cross-sections in order to simplifythe drawings.

When a structure is referred to above as being “on” or “against” anotherstructure, it can be directly on the other structure or interveningstructures may also be present. In contrast, when a structure isreferred to as being “directly on” or “directly against” anotherstructure, there are no intervening structures present. When a structureis referred to as being “connected” or “coupled” to another structure,it can be directly connected or coupled to the other structure, orintervening structures may be present. In contrast, when a structure isreferred to as being “directly connected” or “directly coupled” toanother structure, there are no intervening structures present.

In some embodiments, the invention includes a method of forming aswitch. A bottom electrode is formed over a base. A first electricallyconductive structure is formed directly over the bottom electrode.Dielectric material is formed along a sidewall of the first electricallyconductive structure. The first electrically conductive structure andthe dielectric material together cover a first portion of the bottomelectrode while leaving a second portion of the bottom electrodeexposed. A graphene structure is formed to be electrically coupled withthe exposed portion of the bottom electrode, to be along the dielectricmaterial, and to be laterally spaced from the first electricallyconductive structure by the dielectric material. A second electricallyconductive structure is formed on an opposing side of the graphenestructure from the first electrically conductive structure, and isformed directly over the bottom electrode. A top electrode is formedover the graphene structure. The bottom electrode is electricallycoupled with one of the first and second electrically conductivestructures, and the top electrode is electrically coupled with the otherof the first and second electrically conductive structures. The firstand second electrically conductive structures are configured to providean electric field across the graphene structure.

In some embodiments, the invention includes another method of forming aswitch. First and second electrically conductive structures are formedover a bottom electrode and are formed to be laterally spaced from oneanother. The first electrically conductive structure directly contactsthe bottom electrode, and the second electrically conductive structuredoes not directly contact the bottom electrode. A dielectric liner isformed along a sidewall of one of the first and second electricallyconductive structures. A portion of the bottom electrode remains exposedafter the formation of the dielectric liner. A graphene structure isformed to extend along the dielectric liner and to be electricallycoupled with the bottom electrode. A top electrode is formed over thegraphene structure and the first and second electrically conductivestructures. The top electrode is electrically coupled with the graphenestructure, directly contacts the second electrically conductivestructure, and does not directly contact the first electricallyconductive structure. The first and second electrically conductivestructures are configured to provide an electric field across thegraphene structure.

In some embodiments, the invention includes a method of forming aplurality of switches. A pair of spaced apart bottom electrodes areformed over a base, and a first dielectric material is formed over thebottom electrodes. An opening is formed to extend through the firstdielectric material and to the bottom electrodes. A pair ofupwardly-extending electrically conductive structures are formed alongsidewalls of the opening. One of the upwardly-extending electricallyconductive structures is directly against one of the bottom electrodesand the other of the upwardly-extending electrically conductivestructures is directly against the other of the bottom electrodes.Second dielectric material is formed along sidewalls of theupwardly-extending electrically conductive structures. Portions of thebottom electrodes remain exposed after formation of the seconddielectric material. A pair of graphene structures are formed to extendupwardly from the exposed portions of the bottom electrodes. A first ofthe graphene structures is electrically coupled with, and directly over,one of the bottom electrodes, and a second of the graphene structures iselectrically coupled with, and directly over, the other of the bottomelectrodes. Third dielectric material is formed along sidewalls of thegraphene structures. A pair of downwardly-extending electricallyconductive structures are formed along the third dielectric material.Fourth dielectric material is formed between the downwardly-extendingelectrically conductive structures. A pair of top electrodes are formedover the graphene structures and the downwardly-extending electricallyconductive structures. One of the top electrodes is electrically coupledwith the first graphene structure and with one of thedownwardly-extending electrically conductive structures. The other ofthe top electrodes is electrically coupled with the second graphenestructure and with the other of the downwardly-extending electricallyconductive structures.

In compliance with the statute, the subject matter disclosed herein hasbeen described in language more or less specific as to structural andmethodical features. It is to be understood, however, that the claimsare not limited to the specific features shown and described, since themeans herein disclosed comprise example embodiments. The claims are thusto be afforded full scope as literally worded, and to be appropriatelyinterpreted in accordance with the doctrine of equivalents.

I claim:
 1. A method of forming a switch, comprising: forming a firstelectrically conductive structure over a bottom electrode; forming agraphene structure electrically coupled with the bottom electrode andlaterally spaced from the first electrically conductive structure;forming a second electrically conductive structure over the bottomelectrode and on an opposing side of the graphene structure from thefirst electrically conductive structure; forming a top electrode overthe graphene structure; the bottom electrode being electrically coupledwith one of the first and second electrically conductive structures, thetop electrode being electrically coupled with the other of the first andsecond electrically conductive structures; and wherein the first andsecond electrically conductive structures impart an electric fieldacross the graphene structure.
 2. The method of claim 1 wherein theswitch is formed in an opening over the bottom electrode, and whereinthe switch is the only switch formed in the opening over the bottomelectrode.
 3. The method of claim 1 wherein the switch is one of a pairof switches that are formed in a common opening over a pair of bottomelectrodes.
 4. The method of claim 1 wherein the switch is one of aplurality of switches that are formed in a common opening over aplurality of bottom electrodes.
 5. The method of claim 1 wherein theforming of the graphene structure comprises: forming seed material alongthe dielectric material; and epitaxially growing graphene along the seedmaterial.
 6. A method of forming a switch, comprising: forming first andsecond electrically conductive structures over a bottom electrode andlaterally spaced from one another; the first electrically conductivestructure directly contacting the bottom electrode, and the secondelectrically conductive structure not directly contacting the bottomelectrode; electrically coupling a graphene structure with the bottomelectrode; forming a top electrode over the graphene structure and thefirst and second electrically conductive structures; the top electrodebeing electrically coupled with the graphene structure, directlycontacting the second electrically conductive structure, and notdirectly contacting the first electrically conductive structure; andwherein the first and second electrically conductive structures impartan electric field across the graphene structure.
 7. The method of claim6 wherein the first and second electrically conductive structures areformed simultaneously.
 8. The method of claim 6 wherein the first andsecond electrically conductive structures are formed sequentiallyrelative to one another.
 9. A method of forming switches, comprising:forming a pair of spaced apart bottom electrodes over a semiconductorsubstrate; forming a first dielectric material over the bottomelectrodes; forming an opening extending through the first dielectricmaterial to the bottom electrodes; forming a pair of metal-containingupwardly-extending electrically conductive structures along sidewalls ofthe opening, one of the upwardly-extending electrically conductivestructures being directly against one of the bottom electrodes and theother of the upwardly-extending electrically conductive structures beingdirectly against the other of the bottom electrodes; forming seconddielectric material along sidewalls of the upwardly-extendingelectrically conductive structures, portions of the bottom electrodesbeing exposed after formation of the second dielectric material; forminga pair of graphene structures extending upwardly from the exposedportions of the bottom electrodes; a first of the graphene structuresbeing electrically coupled with, and directly over, one of the bottomelectrodes; a second of the graphene structures being electricallycoupled with, and directly over, the other of the bottom electrodes;forming third dielectric material along sidewalls of the graphenestructures; forming a pair of metal-containing downwardly-extendingelectrically conductive structures along the third dielectric material;forming fourth dielectric material between the downwardly-extendingelectrically conductive structures; and forming a pair of top electrodesover the graphene structures and the downwardly-extending electricallyconductive structures; one of the top electrodes being electricallycoupled with the first graphene structure and with one of thedownwardly-extending electrically conductive structures, and the otherof the top electrodes being electrically coupled with the secondgraphene structure and with the other of the downwardly-extendingelectrically conductive structures.
 10. The method of claim 9 whereinthe forming of the upwardly-extending electrically conductive structurescomprises: deposition of metal-containing electrically conductivematerial along the sidewalls of the opening and across a bottom of theopening; anistropically etching the electrically conductive material;and recessing the electrically conductive material relative to a top ofthe opening so that upper surfaces of the upwardly-extendingelectrically conductive structures are below the top of the opening. 11.The method of claim 10 wherein the forming of the second dielectricmaterial comprises: deposition of the second dielectric material alongand over the upwardly-extending electrically conductive structures, andacross a bottom of the opening; and anistropically etching the seconddielectric material to form dielectric liners along sidewalls of theupwardly-extending electrically conductive structures, and to formdielectric spacers over the upwardly-extending electrically conductivestructures.
 12. The method of claim 11 wherein the top electrodes areformed directly on the dielectric spacers.
 13. The method of claim 11wherein the forming of the graphene structures comprises: deposition ofseed material along sidewalls of the dielectric liners and dielectricspacers; and epitaxial growth of graphene along the seed material. 14.The method of claim 13 further comprising anisotropically etching theseed material to remove the seed material from over tops of thedielectric spacers prior to growing the graphene.
 15. The method ofclaim 13 wherein the graphene grows over tops of the dielectric spacers,and further comprising anisotropically etching the graphene to removethe graphene from over the tops of the dielectric spacers.